Decision analysis model of prolonged oral anticoagulant treatment in factor V Leiden carriers with first episode of deep vein thrombosis.
OBJECTIVE
To assess the risks and benefits of oral anticoagulant treatment extended beyond 3 months after a first episode of deep vein thrombosis in patients who carry factor V Leiden mutation. Such patients have over twice the risk of recurrence after the recommended treatment period, but more information is required before widespread genetic screening can be recommended.


METHODS
A decision analysis Markov model (with data extracted form literature) representing the risks of developing symptomatic venous thromboembolism, the risks of major bleeding, and the efficacy of anticoagulant treatment.


METHODS
A hypothetical cohort of 1000 carriers of factor V Leiden recovering from a first episode of deep vein thrombosis in the lower limbs.


METHODS
Risks and benefits of, firstly, stopping oral anticoagulation 3 months after first episode of thrombosis with reinitiation of treatment only after recurrent thrombosis and, secondly, extension of oral anticoagulation up to 1 to 5 years.


RESULTS
Despite consistent biases in favour of extended oral anticoagulation, analysis revealed that among factor V carriers the number of major haemorrhages induced by oral anticoagulants would exceed that of clinical pulmonary emboli prevented over the entire range of duration of anticoagulation (1 to 5 years). On the other hand, the number of recurrent deep vein thrombi prevented would exceed that of iatrogenic major bleedings.


CONCLUSIONS
The lack of evidence of a net clinical benefit of prolonged oral anticoagulation, at least beyond 1 year, among patients recovering from acute deep vein thrombosis does not support the decision to promote widespread genetic screening programmes to detect the factor V mutation.
Sarasin
F P
FP
Medical Clinics, Hospital Cantonal, University of Geneva Medical School, Switzerland.
Bounameaux
H
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D000284:Administration, Oral; D000925:Anticoagulants / Q000008:administration & dosage* / Q000009:adverse effects; D015331:Cohort Studies; D003663:Decision Trees; D005165:Factor V / Q000235:genetics*; D006470:Hemorrhage / Q000139:chemically induced; D006579:Heterozygote; D006801:Humans; D008390:Markov Chains; D009154:Mutation; D012008:Recurrence; D012307:Risk Factors; D015912:Thrombolytic Therapy / Q000379:methods*; D013924:Thrombophlebitis / Q000188:drug therapy* / Q000235:genetics; D013997:Time Factors; D016896:Treatment Outcome
D000925:Anticoagulants; C095381:factor V Leiden; D005165:Factor V